Process for preparing aryl-iminomethyl-carbamino acid esters

ABSTRACT

The invention relates to a process suitable for large-scale industrial use for preparing compounds of general formula (I)  
                 
 
     wherein:  
     R 1  denotes a group selected from among methyl, ethyl, propyl, cyclopentyl, cyclohexyl, phenyl, benzyl and —C(Me 2 )phenyl, each of which is optionally mono-, di- or trisubstituted by hydroxy; and,  
     R 2  denotes a group selected from among methyl, ethyl, propyl and benzyl.

RELATED APPLICATIONS

[0001] Benefit of U.S. Provisional Application Ser. No. 60/177,378,filed on Jan. 24, 2000 is hereby claimed.

FIELD OF THE INVENTION

[0002] The invention relates to a process for the production ofcompounds of general formula (I)

[0003] wherein the groups R¹ and R² may have the meanings given in thespecification and claims.

BACKGROUND OF THE INVENTION

[0004] From International Patent Application WO 96/02497, benzamidinesand aryl-iminomethylcarbamino acid esters are known which are highlyeffective as pharmaceutical compositions with an LTB₄-antagonisticactivity. Compounds of general formula (I) are of particular importance.

[0005] The problem of the present invention is to provide a processwhich can be used for industrial-scale synthesis of compounds of generalformula(I) in high yields and with end products of high purity.

DETAILED DESCRIPTION OF THE INVENTION

[0006] To solve the problem mentioned above, the invention provides aprocess for preparing compounds of general formula (I)

[0007] wherein

[0008] R¹ denotes a group selected from among methyl, ethyl, propyl,cyclopentyl, cyclohexyl, phenyl, benzyl and —C(Me₂)phenyl, each of whichmay be mono-, di- or trisubstituted by hydroxy;

[0009] R² denotes a group selected from among methyl, ethyl, propyl andbenzyl, characterised in that a compound of general formula (II)

[0010] wherein

[0011] R¹′ denotes a group selected from among methyl, ethyl, propyl,cyclopentyl, cyclohexyl, phenyl, benzyl and —C(Me₂)phenyl, each of whichmay be mono-, di- or trisubstituted by a group —O—PG, the group —O—PGdenoting a protected hydroxyl function selected from amongmethoxymethyloxy, 2-methoxyethoxymethyloxy, 1-ethoxyethyloxy,2-tetrahydropyranyloxy, 1-butoxyethyloxy, tert.-butyloxy, benzyloxy and4-methoxybenzyloxy, is first reacted in an ethereal or aromatic solventwith an alkali metal hexaalkyldisilazane and is then treated with acompound of formula (III)

R²—O—COX′  (III)

[0012] wherein

[0013] R² is as hereinbefore defined and

[0014] X′ denotes chlorine, bromine or —O—R², after working up using anacid of formula HY a compound of formula (IV)

[0015] wherein the groups R¹ and R² are as hereinbefore defined and Ydenotes any desired acid group,

[0016] is isolated and from this the compound of formula (I) isliberated.

[0017] The compounds of formulae (I) and (IV) also include thecorresponding tautomers of formulae (I-T) and (IV-T):

[0018] The term “alkali metal hexaalkyldisilazane” as used above andhereinafter to denote the reagent which is reacted with the compound offormula (II) generally designates a compound of formula (VIII)

[0019] wherein

[0020] Met denotes an alkali metal, preferably lithium, sodium orpotassium, particularly lithium, and

[0021] R³ independently in each case denotes a C₁₋₄-alkyl group,preferably methyl or ethyl, especially methyl.

[0022] Most particularly preferred are lithium hexamethyldisilazane,sodium hexamethyldisilazane and potassium hexamethyldisilazane,particularly lithium hexamethyldisilazane.

[0023] The term “subsequent reaction” with a compound of formula (III)covers both procedures in which the product of the reaction of thecompound of formula (II) with the alkali metal hexamethyldisilazane isreacted with the compound of formula (III) directly, without any furtherintermediate reaction, and also procedures in which the free amidinebase is liberated in the mean time from the product formed. Preferably,the product of the reaction of the compound of formula (II) with thealkali metal hexamethyldisilazane is reacted with the compound offormula (III) directly, especially in a “one-pot synthesis”.

[0024] A preferred process for preparing compounds of general formula(I) is one wherein

[0025] R¹ denotes a group selected from among phenyl, benzyl and—C(Me₂)phenyl, each of which may be mono- or disubstituted, preferablymonosubstituted by hydroxy;

[0026] R² denotes a group selected from among ethyl, propyl and benzyl,characterised in that a compound of general formula (II)

[0027] wherein

[0028] R¹′ denotes a group selected from among phenyl, benzyl and—C(Me₂)phenyl, each of which may be mono- or disubstituted, preferablymonosubstituted by a group —O —PG, the group —O—PG denoting a protectedhydroxyl function selected from among methoxymethyloxy,2-methoxyethoxymethyloxy, 1-ethoxyethyloxy, 2-tetrahydropyranyloxy,1-butoxyethyloxy, tert.-butyloxy, benzyloxy and 4-methoxybenzyloxy,preferably 2-tetrahydropyranyloxy,

[0029] is first reacted in an ethereal or aromatic solvent with analkali metal hexaalkyldisilazane and then treated with a compound offormula (III)

R²—O—COX′  (III)

[0030] wherein

[0031] R² is as hereinbefore defined and

[0032] X′ denotes chlorine, bromine or —O—R²,

[0033] after working up with aqueous hydrochloric acid a compound offormula (IVA)

[0034] wherein the groups R¹ and R² are as hereinbefore defined isisolated and from this the compound of formula (I) is liberated.

[0035] Particularly preferred is a process for preparing compounds ofgeneral formula (I) wherein

[0036] R¹ denotes —C(Me₂)phenyl which may optionally be monosubstitutedby hydroxy and

[0037] R² denotes ethyl,

[0038] characterised in that a compound of general formula (II)

[0039] wherein

[0040] R¹′ denotes —C(Me₂)phenyl, which may optionally bemonosubstituted by a group —O —PG, the group —O—PG denoting a protectedhydroxyl function selected from among methoxymethyloxy,2-tetrahydropyranyloxy, 1-butoxyethyloxy, tert.-butyloxy, benzyloxy and4-methoxybenzyloxy, preferably 2-tetrahydropyranyloxy,

[0041] is first reacted in an ethereal or aromatic solvent with analkali metal hexaalkyldisilazane and then treated with a compound offormula (III)

R²—O—COX′  (III)

[0042] wherein

[0043] R² is as hereinbefore defined and

[0044] X′ denotes chlorine, bromine or —O—R², preferably chlorine, afterworking up with aqueous hydrochloric acid a compound of formula (IVA)wherein the groups R¹ and R² are as hereinbefore defined is isolated andfrom this the compound of formula (I) is liberated.

[0045] In a particularly preferred embodiment of the process accordingto the invention, the compound of formula (II) is prepared in a processcomprising the following steps:

[0046] (a) reacting C₁₋₄-alkyl 3-halomethylbenzoates with4-hydroxybenzonitrile in the manner of a Wilkinson ether synthesis;

[0047] (b) reductively converting the resulting alkyl3-(4-cyano-phenoxy)benzoates of formula (VII)

[0048] wherein R′ denotes C₁₋₄-alkyl, into a compound of formula (V)

[0049] wherein X denotes hydroxy;

[0050] (c) optionally treating the compound of formula (V) wherein Xdenotes hydroxy with a halogenating reagent or a sulphonic acidchloride;

[0051] (d) reacting the compound of formula (V) wherein X denoteshydroxy, chlorine, bromine, mesylate, triflate or tosylate, with aphenol derivative of formula (VI)

[0052] wherein R¹′ denotes a group selected from among methyl, ethyl,propyl, cyclopentyl, cyclohexyl, phenyl, benzyl and —C(Me₂)phenyl, eachof which is optionally mono-, di- or trisubstituted by a group —O—PG,the group —O—PG denoting a protected hydroxyl function selected fromamong methoxymethyloxy, 2-methoxyethoxymethyloxy, 1-ethoxyethyloxy,2-tetrahydropyranyloxy, 1-butoxyethyloxy, tert.-butyloxy, benzyloxy and4-methoxybenzyloxy,; optionally in the form of the corresponding sodiumor potassium phenoxides, under basic reaction conditions, preferably ina polar organic solvent.

[0053] The hydrochlorides of formula (IVA) are of central importance inthe process according to the invention for preparing the compounds ofgeneral formula (I). They are obtained directly in high yields asreadily crystallising salts, from which by-products and/or impuritiescan easily be removed by crystallisation. Accordingly, one aspect of thepresent invention relates to intermediate products of general formula(IVA)

[0054] wherein the groups R¹ and R² may be as hereinbefore defined.

[0055] Of the compounds of general formula (IVA) the compoundethyl{[4-(3-{4-[1-(4-hydroxy-phenyl)-1-methyl-ethyl]-phenoxymethyl}-benzyloxy)-phenyl]-imino-methyl}-carbaminatehydrochloride is particularly preferred.

[0056] The compounds of general formula (II)

[0057] wherein R¹′ may be as hereinbefore defined are obtained accordingto the invention by reacting a compound of formula (V)

[0058] wherein X denotes hydroxy, chlorine, bromine, mesylate, triflate,benzenesulphonate or tosylate, with a compound of formula (VI)

[0059] wherein R¹′ may be as hereinbefore defined and wherein thecompound of formula (VI) may optionally also be used in the form of thesodium and potassium phenoxides thereof, under basic reaction conditionsin a polar organic solvent.

[0060] It is preferred to prepare compounds of general formula (II)wherein R¹ may be as hereinbefore defined by reacting a compound offormula (V) wherein X denotes hydroxy, chlorine or mesylate, morepreferably hydroxy or chlorine, most preferably chlorine, with acompound of formula (VI) wherein R¹′ may be as hereinbefore defined andwherein the compound of formula (VI) is used in the form of the alkalimetal phenoxides thereof, preferably in the form of the sodiumphenoxides thereof.

[0061] When the compounds of general formula (I) are synthesisedaccording to the invention, the intermediate products of general formula(V) are of central importance. In another aspect, therefore, the presentinvention relates to the compounds of general formula (V)

[0062] as such, wherein X may be as hereinbefore defined and mostpreferably may denote hydroxy or chlorine.

[0063] The compound of formula (VII), one of the starting compounds, isalso of particular importance in the synthesis according to theinvention of the compounds of general formula (I). Therefore, in anotheraspect, the present invention relates to the compounds of formula (VII)

[0064] as such, wherein R′ denotes C₁₋₄-alkyl, preferably methyl orethyl, most preferably methyl.

[0065] In order to perform the process for preparing the compounds ofgeneral formula (I) according to the invention starting from thenitrites of general formula (II) the following method is used:

[0066] A compound of general formula (II) is slowly metered into asolution of the alkali metal hexaalkyldisilazane, preferably lithiumbis(trimethylsilyl)-amide, sodium bis(trimethylsilyl)-amide, mostpreferably lithium bis(trimethylsilyl)-amide, in an ethereal or aromaticorganic solvent, preferably in a solvent selected from amongtetrahydrofaran, toluene, dioxane, more preferably in tetrahydrofuran ordioxane, most preferably in tetrahydrofuran, preferably with cooling,especially at a temperature between −50° C. and 30° C., more especiallyat −20° C. to 10° C., most especially at about 0° C. The quantity of thealkali metal hexaalkyldisilazane used is determined by the amount ofnitrile of formula (II) used. At least 1 mol, preferably 1.01 to 1.15mol of alkali metal hexaalkyldisilazane is used per mol of nitrile offormula (II). The quantity of ethereal solvent used is between 0.7 and1.5, preferably 0.9 to 1.3 kg per mol of compound of formula (II) used.

[0067] After all the compound of formula (II) has been added theresulting suspension is stirred at constant temperature, optionally at atemperature of up to 40° C., preferably at about 20-25° C. over a periodof 6 to 24 hours, preferably 8 to 18 hours. The stirring is preferablycontinued for 10 to 12 hours. During this time the solid which wasinitially in suspension may go into solution.

[0068] The mixture can then optionally be diluted either with additionalethereal solvent or with a nonpolar organic solvent, preferably with anaromatic organic solvent. A solvent selected from among toluene,benzene, cyclohexane, methylcyclohexane or xylene is preferably used, ofwhich toluene and xylene are particularly preferred, toluene being mostpreferred. If the mixture is diluted, it is sufficient to add up to 0.5L, preferably up to 0.3 L of solvent per mol of compound of formula (II)used.

[0069] The reaction mixture is heated to a reaction temperature ofbetween −50° C. and 20° C., more especially −20° C. to 10° C., mostpreferably −10 to 0° C. before the addition of the compound of generalformula (III). Then the compound of formula (III) is added, in an amountof at least 1 mol, preferably 1.05 to 1.3 mol, more particularly 1.1 to1.2 mol, per mol of compound (II) used.

[0070] After the reaction is complete, the product is hydrolysed by theaddition of an acid of formula HY, preferably an inorganic or organicacid such as hydrochloric acid, sulphuric acid, phosphoric acid, aceticacid, trifluoroacetic acid, oxalic acid and fumaric acid, particularlyaqueous hydrochloric acid. About 1 mol of acid, particularlyhydrochloric acid, is used per mol of the compound of formula (II)originally used. According to the invention, it is preferable to adddilute hydrochloric acid (preferably 8-15%, more especially 10-12%strength).

[0071] After a period of about 10 minutes to 1 hour the aqueous lowerphase is separated off and an organic solvent selected from amongacetone, methylisobutylketone, methylethylketone, optionally a mixtureof two of the above solvents, most preferably a mixture of acetone andmethylisobutylketone in a ratio of 3-1:1, most preferably in a ratio of2.5-1.5:1, is added to the organic phase. Crystallisation of thecompounds of formula (IVA) is initiated by the addition of aqueoushydrochloric acid. About 1 to 1.2 mol of hydrochloric acid is used permole of the compound of formula (II) originally used. It is preferredaccording to the invention to add preferably 32-37%, most preferably 37%hydrochloric acid. The compounds of formula (IV) are separated from thereaction mixture by conventional methods, e.g. by centrifugation, washedwith an organic solvent selected from among acetone,methylisobutylketone, methylethylketone or a carboxylic acid ester,preferably acetone, and dried.

[0072] The release of the compounds of formula (I) from the acidaddition salts of formula (IV), particularly from the hydrochlorides offormula (IVA), is generally carried out with basic reactants underreaction conditions which are as neutral as possible, preferably in thepresence of buffer systems, according to the method describedhereinafter:

[0073] An organic solvent selected from among acetone,methylisobutylketone, methylethylketone, tetrahydrofuran or a carboxylicacid ester, preferably acetone, and then a compound of formula (IV) areadded to a solution of trisodium citrate dihydrate, sodium hydroxide,potassium hydroxide, alkali or alkaline earth metal salts of organic orinorganic weak acids, preferably trisodium citrate dihydrate, trisodiumcitrate or sodium hydroxide, most preferably trisodium citrate dihydratein water at 0-40° C., preferably at 20-25° C., particularly at about 20°C. About 1-2 mol, preferably about 1.5 mol of the sodium or potassiumcitrate used and about 1 to 3 L of the abovementioned organic solvent,preferably about 2 L, are used per mol of compound of formula (IV) putin. The mixture is stirred at constant temperature over a period of 20minutes to 2 hours, preferably 1-1.2 hours.

[0074] When strong bases such as sodium hydroxide are used, the methodof addition may be reversed if desired. The crystalline product isseparated off by filtration, for example, washed with water to removeany salt, and with the abovementioned organic solvent and finally dried.

[0075] The compounds of general formula (II) may be obtained by reactinga compound of formula (V) with a compound of formula (VI), as alreadymentioned. According to the invention, the following procedure may beused.

[0076] The compound of formula (V) wherein X denotes hydroxy isdissolved in an organic solvent, if possible an aprotic-polar organicsolvent, preferably N,N-dimethylacetamide, acetone, methylethylketone,methylisobutylketone, N-methylpyrrolidone, N,N-dimethylformamide,tetraalkylurea, most preferably in N,N-dimethylacetamide. 0.5 to 1.0,preferably about 0.7 L of solvent are used at this point per mol ofstarting compound according to the invention. Then the solution thusobtained is cooled to a temperature of <10° C., preferably to atemperature between +5° C. and −20° C., most preferably to about −10° C.to 0° C. Then a suitably substituted sulphonic acid chloride, optionallythe abovementioned organic solvent, an organic base, optionally theabovementioned organic solvent and the aqueous solution of an inorganicbase are added one after the other. A suitably substituted sulphonicacid chloride according to the invention might be methanesulphonic acidchloride, para-toluenesulphonic acid chloride, benzenesulphonic acidchloride or trifluoromethanesulphonic acid chloride. Preferably,methanesulphonic acid chloride is used. The organic bases may be, forexample, dimethylaminopyridine, pyridine, methylpyridine, tert. amines,e.g. trimethylamine, triethylamine, diisopropylethylamine, or cyclicamines such as N-methylpyrrolidine or DBU (diazabicycloundecene).Preferred organic amines are N-methylpyrrolidine, trimethylamine,triethylamine or diisopropylethylamine, most preferably triethylamine.The organic base is used in at least a stoichiometric amount, based onthe starting compound of formula (V). Preferably, the organic base isused in an excess of 10-50 mol %, most preferably in about a 30% excessin relation to the compound of formula (V) used. The aqueous solution ofan organic base used will usually be an alkali metal or alkaline earthmetal hydroxide solution, the alkali metal hydroxide solutions beingpreferred. The aqueous solutions of potassium hydroxide and sodiumhydroxide are particularly important according to the invention.Usually, 20-50% solutions of the abovementioned inorganic hydroxides areused. More concentrated solutions such as, for example, 45% solutionsare preferred according to the invention. Based on the compound offormula (V) used, the inorganic base is used in at least astoichiometric amount, preferably in an excess of 50-100 mol %. Theinorganic base is particularly preferably used in an excess of about 75mol %, based on the compound of formula (V) added. If desired, thereaction mixture may be diluted after the addition of the suitablysubstituted sulphonic acid chloride or the organic base by the additionof the abovementioned organic solvent. In this case, 2-10%, preferablyabout 5% of the quantity of solvent put in initially is added.

[0077] In any case, after all the aqueous solution of the inorganic basehas been added, the reaction mixture is diluted with the organic solventmentioned above. About 0.5 to 1.0 L, preferably between 0.7 and 0.8 L ofthe solvent used are added, per mol of starting compound of formula (V)used. Then alkoxides or metal salts of formula (VI) are added. Thesodium and potassium phenoxides which may be derived from the compoundsof formula (VI) are preferably used. According to the invention,stoichiometric quantities, optionally substoichiometric quantities or anexcess of the compound (VI) may be added, based on the educt of formula(V). After all the compound (VI) has been added, the reaction iscontinued for a period of about 1-3 hours, preferably about 1.5 to 2hours at a temperature of 5-35° C., preferably at about 25° C., andfinally stirred for a period of about 1-3 hours, preferably about 1.5-2hours at a temperature of 50-100° C., preferably at about 70-90° C.After the reaction has ended the product of formula (II) is crystallisedby the addition of a suitable polar solvent selected from among thelower alcohols and water.

[0078] In order to obtain high yields of particularly pure products, ithas proved preferable according to the invention to add, for thecrystallisation, a solvent mixture consisting of a nonpolar organicsolvent, preferably xylene or toluene, most preferably toluene, a polarorganic solvent, preferably a lower alcohol such as methanol, ethanol,butanol or isopropanol, especially isopropanol and water. The ratio byvolume of nonpolar to polar organic solvent to water can vary within therange from 1:7-10:5-8, preferably 1:8-9:6-7. By cooling to below 50° C.,preferably to about 30° C., the crystallisation of the product offormula (II) is completed. After isolation, the crystallised product isoptionally washed with the abovementioned lower alcohol and with water.

[0079] If the compounds of formula (II) are to be obtained from thecompounds of formula (V) wherein X has a meaning other than hydroxy, thefollowing procedure may be used according to the invention.

[0080] The sodium or potassium phenoxide derived from the compounds offormula (VI) is taken up in water together with a compound of formula(V), mixed with a nonpolar organic solvent and optionally reacted underphase transfer conditions. The phase transfer catalysts which may beused according to the invention include the quaternary ammonium salts,preferably the halides, sulphates or hydroxides oftetradecyltrimethylammonium, hexadecyltrimethylammonium,tetrabutylammonium, tributylmethylammonium or triethylbenzylammonium.The nonpolar organic solvent may be a chlorinated hydrocarbon such asmethylene chloride or preferably, according to the invention, anaromatic hydrocarbon such as benzene, toluene, xylene, preferablytoluene. The compounds of formula (V) and (VI) are used in a virtuallystoichiometric ratio, and if desired one of the two reactants may alsobe used in a slight excess (e.g. 15%). The amount of solvent to be useddepends on the quantity of educt put in. Between 1 and 2 L of water andbetween 0.3 and 1.0 L of the organic solvent, preferably between 1.5 and1.8 L of water and 0.5 to 0.7 L of the organic solvent are used per molof compound of formula (VI) put in. The reaction is carried out withintensive stirring over a period of 3 to 9, preferably 5 to 7 hours at atemperature of 50 to 100° C., preferably at 70 to 80° C. Then, tocrystallise the product, a polar organic solvent, preferably a loweralcohol, most preferably isopropanol is added to the separated organicphase. By cooling to below 50° C., preferably to about 30° C., thecrystallisation of the product of formula (II) is completed. After beingisolated, the crystallised product of formula (II) is optionally washedwith the abovementioned lower alcohol and with water.

[0081] The starting compounds of formula (V)

[0082] which, as already mentioned, relate to one aspect of the presentinvention, may be prepared analogously to methods of synthesis known perse. The compound of formula (V) wherein X denotes hydroxy may beprepared by reacting methyl 3-halomethyl-benzoates with4-hydroxybenzonitrile, for example, in a Wilkinson ether synthesis. Themethyl 3-(4-cyano-phenoxy)-benzoate (VII) thus obtained can bereductively converted into the compound of general formula (V) whereinX=hydroxy (=4-(3-hydroxymethyl-benzyloxy)-benzonitrile) by the analogoususe of current standard procedures.

[0083] The compounds of formula (V) wherein X denotes chlorine orbromine may be prepared analogously to methods of synthesis known per sefrom the compound of formula (V) wherein X denotes hydroxy, using commonhalogenation reagents such as, for example, thionylchloride, phosphorusoxychloride or phosphorus pentachloride, methanesulphonic acid chloride,benzenesulphochloride, preferably thionylchloride or methanesulphonicacid chloride.

[0084] The compounds of formula (V) wherein X denotes mesylate, triflateor tosylate may be prepared analogously to methods of synthesis knownper se from the compound of formula (V) wherein X denotes hydroxy, byreacting with the appropriate sulphonic acid chlorides in aprotic,preferably polar organic solvents, preferably selected from amongdichloromethane, N,N-dimethylacetamide, dimethylformamide, acetonitrile,N-methylpyrrolidone, tetraalkylurea in the presence of organic bases,preferably selected from among dimethylaminopyridine, pyridine,methylpyridine, N-methylpyrrolidine, trimethylamine, triethylamine,diisopropylethylamine and DBU (diazabicycloundecene).

[0085] The following Examples serve to illustrate methods of synthesisaccording to the invention, carried out by way of example, for preparingthe compound of formula (I). They must be considered as possible methodsgiven by way of example, without restricting the invention to theircontent.

EXAMPLE 1 Methyl 3-(4-cyano-phenoxymethyl)-benzoate:

[0086] 10.00 kg (43.6 mol) of methyl 3-(bromomethyl)benzoate and 5.21 kg(43.74 mol) of 4-hydroxybenzonitrile are dissolved in 100 liters ofacetone and stirred with 8.4 kg (60.7 mol) of potassium carbonate in thepresence of 0.1 kg of sodium iodide for about 4 h under refluxconditions. Then 35 liters of acetone are distilled off and 100 litersof water are added at reflux conditions. The reaction mixture is cooledto 20° C. and the crystallisation is completed by the addition ofanother 30 liters of water. The crystals formed are separated off,washed with 50 liters of water and dried in vacuo.

[0087] Yield: 11.1 kg (95%) of methyl3-(4-cyano-phenoxymethyl)-benzoate;

[0088] Melting point 109 . . . 112° C., white solid,

[0089] TLC (silica gel 60 F254-ready-made plate (Merck): Rf=0.5(toluene:acetone=9:1)

EXAMPLE 2: 4-(3-hydroxymethyl-benzyloxy)-benzonitrile:

[0090] 20.05 kg (26.7 mol) of methyl 3-(4-cyano-phenoxymethyl)-benzoateare dissolved in 100 liters of THF and 40 liters of methanol. At 40 to45° C., 8.51 kg of sodium boranate are added in batches. The reaction iscompleted by stirring the reaction mixture at 61 to 63° C. for about 5hours. The reaction mixture is then cooled to 25° C. and 90 liters of a15% sodium hydroxide solution are added. After stirring, the aqueoussupernatant is separated off and mixed with 30 liters of a 22.5% sodiumhydroxide solution. After stirring, the aqueous supernatant is separatedoff and from this about 100 liters of solvent are distilled off at asump temperature of 63 to 75° C. The distillation residue iscrystallised by the addition of 20 liters of isopropanol at 50 to 60° C.and 150 liters of water at 40 to 50° C. After the suspension has beencooled to 20 to 30° C. the crystals are separated off, washed with 60 to100 liters of water and batchwise with 25 liters of cold isopropanol anddried in vacuo.

[0091] Yield: 15.8 kg (88%) of4-(3-hydroxymethyl-benzyloxy)-benzonitrile;

[0092] Melting point (DSC): 110-115° C., white solid

[0093] IR: 3444/cm (OH band); 2229/cm (CN band)

EXAMPLE 3: 4-(3-Chloromethyl-benzyloxy)-benzonitrile:

[0094] Variant A:

[0095] 7.18 g (30 mmol) of 4-(3-hydroxymethyl-benzyloxy)-benzonitrileare dissolved in 80 ml of dichloromethane, mixed with 4.13 g (35 mmol)of thionylchloride and 0.1 g of DMF and stirred while heating to 40° C.until the development of gas has ceased. After cooling, the organicreaction mixture is washed successively with water and dilute sodiumhydroxide solution and crystallised by evaporation.

[0096] Yield: 6.8 g (88%) of 4-(3-chloromethyl-benzyloxy)-benzonitrile;

[0097] TLC (silica gel 60 F254-ready-made plate (Merck): Rf=0.9(toluene-acetone=9:1), Rf=0.44 (toluene)

[0098] Variant B:

[0099] 7.18 g (30 mmol) of 4-(3-hydroxymethyl-benzyloxy)-benzonitrileare dissolved in 22 ml of N,N-dimethylacetamide, mixed with 4.47 g (39mmol) of methanesulphonic acid chloride and 3.95 g (39 mmol) oftriethylamine and stirred for 10 hours at 20-30° C. Then thetriethylammonium chloride precipitated is filtered off, the filtrate ismixed with 30 ml of isopropanol and the desired4-(3-chloromethyl-benzyloxy)-benzonitrile is crystallised by the meteredaddition of 30 ml of water. The suspension is stirred for 15 min at 10°C. and filtered. The crystals are washed with a mixture of 5 ml ofisopropanol and 20 ml water and dried at 20° C. in vacuo. Yield: 6.8 g(88%) of 4-(3-chloromethyl-benzyloxy)-benzonitrile Melting point: 65-68°C.

EXAMPLE 4Sodium-4-{1-methyl-1-[4-tetrahydro-pyran-2-yloxy)-phenyl]-ethyl}-phenoxide

[0100] 121.8 kg of bisphenol A are suspended in 480 l of toluene and 46l of THF. After the addition of the catalyst (1.3 kg of 37% hydrochloricacid), 44.9 kg of 3,4-dihydro-2H-pyran are metered in so as not toexceed a temperature of 40° C. The solid then goes into solution. Thenthe reaction mixture is mixed with 26. 4 kg of 45% sodium hydroxidesolution and 260 l of water. The organic upper phase is separated offand about 50 l of solvent are eliminated by distillation. At 30 to 40°C. the organic phase is washed several times with dilute sodiumhydroxide solution so that sufficient purity can be achieved (monitoredby TLC). If the aqueous lower phase is in the pH range 11.8 to 12.2,excess bisphenol A can easily be separated off.

[0101] The toluene phase purified by extraction is mixed with 11 litersof isopropanol and 80 liters of water and heated to 50 to 55° C. By theaddition of 47.4 kg of 45% sodium hydroxide solution and cooling thereaction mixture to 20 to 25° C., a crystal suspension is obtained. Thecrystals are separated by filtration, washed with about 160 l of tolueneand then dried in vacuo.

[0102] Yield: 96.5 kg (54%) (as the tetra-hydrate)

EXAMPLE 5 Synthesis of4-[3-(4-{1-methyl-1-[4-(tetrahydro-pyran-2-yloxy)-phenyl]-ethyl}-phenoxymethyl)-benzyloxy]-benzonitrile:

[0103] Variant A: (Starting From Example 2)

[0104] 28 kg (244 mol) of methanesulphonic acid chloride, 6 liters ofN,N-dimethylacetamide, 24.7 kg (244 mol) of triethylamine, 6 liters ofN,N-dimethylacetamide, 29.4 kg of 45% sodium hydroxide solution, 143liters of N,N-dimethylacetamide, 59.7 kg (178.5 mol) of Example 4(≡sodium-4-{1-methyl-1-[4-tetrahydro-pyran-2-yloxy)-phenyl]-ethyl}-phenoxide,as the tetrahydrate) are metered successively into a solution of 45 kg(188 mol) of 4-(3-hydroxymethyl-benzyloxy)-benzonitrile (Example 2) in133 liters of N,N-dimethylacetamide at about −10° to 0° C. Then thereaction mixture is stirred for 2 h at 25° C. and for another 1.5 h at75 to 80° C. After the addition of 32 liters of toluene, 255 liters ofisopropanol and 200 liters of water crystallisation begins which iscompleted by cooling to 30° C. The crystalline product is separated offby filtration, washed with isopropanol and water and then dried invacuo. Yield: 85 kg (90%) of4-[3-(4-{1-methyl-1-[4-(tetrahydro-pyran-2-yloxy)-phenyl]-ethyl}-phenoxymethyl)-benzyloxy]-benzonitrile;

[0105] Variant B: (Starting From Example 3)

[0106] 19.4 kg (50 mol) of Example 4 (asodium-4-{1-methyl-1-[4-tetrahydro-pyran-2-yloxy)-phenyl]-ethyl}-phenoxide,as the tetrahydrate) and 12.2 kg (47.5 mol) of Example 3(=-4-(3-chloromethyl-benzyloxy)-benzonitrile) are mixed with 85 litersof water, a phase transfer catalyst (e.g.: 2.1 kg (2.5 mol) of a 40%aqueous solution of tetradecyltrimethylammonium bromide and 32 liters oftoluene and intensively stirred for 6 h at about 80° C. Then 44 litersof isopropanol are metered into the separated organic upper phase, at 50to 70° C., the crystal suspension obtained is cooled to about 25° C. andfiltered. The crystals separated off are washed twice with 25 liters ofcold isopropanol and dried in vacuo.

[0107] Yield: 22.8 kg (90%) of4-[3-(4-{1-methyl-1-[4-(tetrahydro-pyran-2-yloxy)-phenyl]-ethyl}-phenoxymethyl)-benzyloxy]-benzonitrile;

EXAMPLE 6 Ethyl{[4-(3-{4-[1-(4-hydroxy-phenyl)-1-methyl-ethyl]-phenoxymethyl}-benzyloxy)-phenyl]-imino-methyl}-carbaminatehydrochloride

[0108] 132 kg (247 mol) of4-(3-{4-[1-(4-tetrahydropyranyl-phenyl)-1-methyl-ethyl]-phenoxymethyl}-benzyloxy)-benzonitrile(Example 5)are metered into a solution of 45.5 kg (272 mol) oflithium-bis(trimethylsilyl-)amide in 266 kg of THF at about 0° C. Theresulting suspension is stirred for about 10 h at about 25° C. The solidthen goes into solution. After the addition of 68 liters of toluene thereaction mixture is cooled to −10° to 0° C. and at this temperature 30.8kg (284 mol) of ethyl chloroformate are added to the reaction vessel.Once the reaction has finished completely 24.3 kg of 37% hydrochloricacid (diluted with 50 liters of water) are metered in and about 20 minlater the aqueous lower phase is separated off. Crystallisation of theintended product is initiated by the subsequent addition of 106 litersof acetone, 48 liters of methylisobutylketone and 24.3 kg of 37%hydrochloric acid.

[0109] 123 kg (87%) of ethyl{[4-(3-{4-[1-(4-hydroxy-phenyl)-1-methyl-ethyl]-phenoxymethyl}-benzyloxy)phenyl]-imino-methyl}-carbaminate hydrochloride are obtained aftercentrifuging, washing with acetone and drying in vacuo.

[0110] Melting point: 170-175° C.

EXAMPLE 7 Ethyl{[4-(3-{4-[1-(4-hydroxy-phenyl)-1-methyl-ethyl]-phenoxymethyl}-benzyloxy)-phenyl]-imino-methyl}-carbaminate:

[0111] 466 liters of acetone and 142 kg of ethyl{[4-(3-{4-[1-(4-hydroxy-phenyl)-1-methyl-ethyl]-phenoxymethyl}-benzyloxy)-phenyl]-imino-methyl}-carbaminatehydrochloride (Example 6) are added to a solution of 109 kg of trisodiumcitrate dihydrate at 20° C. After one hour's stirring the crystallineproduct is separated off by filtration, washed with water to remove anysalts, washed again with about 100 liters of acetone and finally driedin vacuo.

[0112] 116 kg (90%) of ethyl{[4-(3-{4-[1-(4-hydroxy-phenyl)-1-methyl-ethyl]-phenoxymethyl}-benzyloxy)-phenyl]-imino-methyl}-carbaminateare obtained.

What is claimed is:
 1. A process for preparing a compound of the formula(I)

wherein R¹ denotes a group selected from among methyl, ethyl, propyl,cyclopentyl, cyclohexyl, phenyl, benzyl and —C(Me₂)phenyl, each of whichis optionally mono-, di- or trisubstituted by hydroxy; R² denotes agroup selected from among methyl, ethyl, propyl and benzyl, whichprocess comprises the following steps: (a) reacting a compound of theformula (II)

wherein R¹′ denotes a group selected from among methyl, ethyl, propyl,cyclopentyl, cyclohexyl, phenyl, benzyl and —C(Me₂)phenyl, each of whichis optionally mono-, di- or trisubstituted by a group —O—PG, the group—O—PG denoting a protected hydroxyl function selected from amongmethoxymethyloxy, 2-methoxyethoxymethyloxy, 1-ethoxyethyloxy,2-tetrahydropyranyloxy, 1-butoxyethyloxy, tert.-butyloxy, benzyloxy and4-methoxybenzyloxy, with an alkali metal hexaalkyldisilazane of theformula (VIII)

wherein Met denotes an alkali metal, and R³ independently in each casedenotes a C₁₋₄-alkyl group; (b) treating the product of step (a) with acompound of the formula (III) R²—O—COX′  (III) wherein: R² is ashereinbefore defined in this claim and X′ denotes chlorine, bromine or—O—R², wherein R² is as hereinbefore defined in this claim; (c) treatingthe product of step (b) with a protic acid of formula HY, wherein Ydenotes the counter ion, to yield a compound of the formula (IV)

or a tautomer thereof, wherein the groups R¹, R² and Y are ashereinbefore defined in this claim; (d) isolating the compound of theformula IV produced in step (c); (e) treating the isolated compound ofthe formula IV, produced in step (d) with a base to produce the compoundof the formula I.
 2. The process according to claim 1 , wherein: (a) inthe compound of formula I, R¹ denotes a group selected from amongphenyl, benzyl and —C(Me₂)phenyl, each of which is optionally mono- ordisubstituted by hydroxy; R² denotes a group selected from among ethyl,propyl and benzyl; (b) in the compound of formula II, R¹′ denotes agroup selected from among phenyl, benzyl and —C(Me₂)phenyl, each ofwhich is optionally mono- or disubstituted by a group —O—PG, the group—O—PG denoting a protected hydroxyl function selected from amongmethoxymethyloxy, 2-methoxyethoxymethyloxy, 1-ethoxyethyloxy,2-tetrahydropyranyloxy, 1-butoxyethyloxy, tert.-butyloxy, benzyloxy and4-methoxybenzyloxy; (c) in the compound of formula III, R² is ashereinbefore defined in this claim, and X′ denotes a chlorine or bromineatom or the group —OR², wherein R² is as hereinbefore defined in thisclaim; and, (d) the acid HY is hydrochloric acid and the intermediateproduced in step (c) is a compound of the formula IVA

or a tautomer thereof, wherein the groups R¹, R² and Y are ashereinbefore defined in this claim.
 3. The process according to claim 1, wherein: (a) in the compound of formula I, R¹ denotes —C(Me₂)phenyl,which is optionally monosubstituted by hydroxy; R² denotes ethyl; (b) inthe compound of formula II, R¹′ denotes —C(Me₂)phenyl, which isoptionally monosubstituted by a group —O—PG, the group —O—PG denoting aprotected hydroxyl function selected from among methoxymethyloxy,2-tetrahydropyranyloxy, 1-butoxyethyloxy, tert.-butyloxy, benzyloxy and4-methoxybenzyloxy; and, (c) in the compound of formula III, R² is ashereinbefore defined in this claim, and X′ denotes a chlorine or bromineatom or the group —OR², wherein R² is as hereinbefore defined in thisclaim.
 4. A process for preparing a compound of formula II

which process comprises the following steps: (a) reacting a C₁₋₄-alkyl3-halomethylbenzoate of the formula

wherein R′ denotes a C₁₋₄-alkyl group and Hal denotes a halogen atom,with 4-hydroxybenzonitrile

in the manner of a Wilkinson ether synthesis; (b) reductively convertingthe resulting alkyl 3-(4-cyano-phenoxy)benzoate of the formula VII

wherein R′ is as hereinbefore defined in this claim, into a compound ofthe formula (V)

wherein X denotes hydroxy; (c) optionally treating the compound offormula (V) wherein X denotes hydroxy with a chlorinating or brominatingreagent or a sulphonic acid chloride (selected from methane sulfonicacid chloride, trifluoromethane sulfonic acid chloride and paratoluenesulfonic acid chloride), to yield a compound of the formula V wherein Xdenotes chlorine, bromine, mesylate, triflate or tosylate; and, (d)reacting the compound of formula (V) wherein X denotes hydroxy,chlorine, bromine, mesylate, triflate or tosylate, with a phenolderivative of formula (VI)

wherein R¹′ denotes a group selected from among methyl, ethyl, propyl,cyclopentyl, cyclohexyl, phenyl, benzyl and —C(Me₂)phenyl, each of whichis optionally mono-, di- or trisubstituted by a group —O—PG, the group—O—PG denoting a protected hydroxyl function selected from amongmethoxymethyloxy, 2-methoxyethoxymethyloxy, 1-ethoxyethyloxy,2-tetrahydropyranyloxy, 1-butoxyethyloxy, tert.-butyloxy, benzyloxy and4-methoxybenzyloxy; and wherein said phenol derivative of the formula VIis optionally in the form of the corresponding sodium or potassiumphenoxide, under basic reaction conditions, in a polar organic solvent,to yield a compound of the formula II.
 5. A compound of the formula(IVA) or the tautomeric form thereof

wherein the groups R¹ and R² are defined as in claim 1 , 2 or
 3. 6. Acompound of the formula formula (V),

wherein X denotes hydroxy, chlorine, bromine, mesylate, triflate ortosylate.
 7. A compound according to claim 6 , wherein X denotes hydroxyor chlorine.
 8. A compound of the formula (VII)

wherein R′ denotes C₁₋₄-alkyl.